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| achromatopsia [2025/11/12 15:21] – created Scott Larson | achromatopsia [2025/12/01 17:17] (current) – [Resources] Scott Larson | ||
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| ====== Achromatopsia ====== | ====== Achromatopsia ====== | ||
| + | ====Main Features==== | ||
| + | * Reduced vision due to lack of functioning cones | ||
| + | * Vision usually 20/200 with complete color blindness in complete forms | ||
| + | * Incomplete forms may have better vision and some color vision | ||
| + | * Nystagmus that may improve with age | ||
| + | * Central relative scotoma with normal peripheral visual fields | ||
| + | * Complete and Incomplete forms | ||
| + | * Usually stable but some see slow worsening of visual acuity and macular atrophy | ||
| + | ====Distinguishing Features==== | ||
| + | * Photophobia at birth or early infancy | ||
| + | * Better vision in dim illumination | ||
| + | * Sluggish pupil responses with paradoxical constriction in the dark | ||
| + | * Usually normal fundus appearance | ||
| + | * OCT may show ellipsoid zone disruption or absence, outer retinal atrophy and RPE loss | ||
| + | * ERG | ||
| + | * lack of cone function- 30 Hz flicker and single flash photoptic waveform is small and delayed | ||
| + | * normal ROD function- normal dark adapted dim and bright flash waveforms | ||
| + | ====Differential Dx==== | ||
| + | * [[congenital_stationary_night_blindness|Congenital Stationary Night Blindness]] | ||
| + | * [[leber_congenital_amaurosis|Leber Congenital Amaurosis]] | ||
| + | * [[retinitis_pigmentosa|Retinitis Pigmentosa]] | ||
| + | * Idiopathic Nystagmus Syndrome | ||
| + | ====Pathogenesis==== | ||
| + | * 1 in 30,000 live births | ||
| + | * Recessively inherited mutation in a gene that codes for a part of the cone phototransduction pathway. | ||
| + | * 70-80% from mutations in the following genes: CNGA3 and CNGB3 | ||
| + | * 1-2% from mutations in GNAT2, PDE6C, PDE6H, ATF6 | ||
| + | ====Treatment==== | ||
| + | * Supportive care | ||
| + | * Sunglasses | ||
| + | ====Resources==== | ||
| + | - [[https:// | ||
| + | - [[https:// | ||
| {{tag> | {{tag> | ||